Nuclear power plants - Instrumentation and control important to safety - Management of ageing of sensors and transmitters - Part 2: Temperature sensors

IEC 62765-2:2019 identifies minimum requirements and applicable practices for correcting and preventing any potential impacts on nuclear power plant (NPP) safety due to the ageing of temperature sensors, such as NPP resistance temperature detectors (RTDs) and thermocouples (TCs).
This document provides strategies, technical requirements, and recommended practices for the management of the ageing of temperature sensors important to safety in nuclear power plants (NPPs) to ensure that ageing can be identified and that suitable remedial actions are undertaken as necessary to demonstrate that the safety of the plant will not be impaired. This document is aligned with IEC 62342, which provides guidance on ageing management for instrumentation and control (I&C) systems important to safety in NPPs

Centrales nucléaires de puissance - Instrumentation et contrôle-commande importants pour la sûreté - Gestion du vieillissement des capteurs et des transmetteurs - Partie 2: Capteurs de température

l'IEC 62765-2:2019 identifie les exigences minimales et les pratiques applicables pour la correction et la prévention des effets possibles sur la sûreté des centrales nucléaires de puissance (CNP) dus au vieillissement des capteurs de température, tels que les sondes à résistance (SR) et les couples thermoélectriques (TC) de ces centrales.
Le présent document fournit les stratégies, les exigences techniques et les pratiques recommandées pour la gestion du vieillissement des capteurs de température importants pour la sûreté dans les centrales nucléaires de puissance pour s'assurer que le vieillissement peut être identifié et que les actions pour y remédier sont mises en œuvre lorsque cela est nécessaire pour démontrer que la sûreté de l'installation ne sera pas dégradée. Le présent document est aligné avec l'IEC 62342 qui fournit des recommandations sur la gestion du vieillissement des systèmes d'instrumentation et de contrôle-commande (I&C) importants pour la sûreté dans les centrales nucléaires de puissance.

General Information

Status
Published
Publication Date
28-Jan-2019
Current Stage
PPUB - Publication issued
Completion Date
29-Jan-2019
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IEC 62765-2
Edition 1.0 2019-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Nuclear powers plants – Instrumentation and control important to safety –
Management of ageing of sensors and transmitters –
Part 2: Temperature sensors
Centrales nucléaires de puissance – Instrumentation et contrôle-commande
importants pour la sûreté – Gestion du vieillissement des capteurs et des
transmetteurs –
Partie 2: Capteurs de température
IEC 62765-2:2019-01(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 62765-2
Edition 1.0 2019-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Nuclear powers plants – Instrumentation and control important to safety –
Management of ageing of sensors and transmitters –
Part 2: Temperature sensors
Centrales nucléaires de puissance – Instrumentation et contrôle-commande
importants pour la sûreté – Gestion du vieillissement des capteurs et des
transmetteurs –
Partie 2: Capteurs de température
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 27.120.20 ISBN 978-2-8322-6171-2

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – IEC 62765-2:2019 © IEC 2019
CONTENTS

FOREWORD ........................................................................................................................... 4

INTRODUCTION ..................................................................................................................... 6

1 Scope .............................................................................................................................. 8

2 Normative references ...................................................................................................... 8

3 Terms and definitions ...................................................................................................... 9

4 Abbreviated terms ......................................................................................................... 13

5 Technical background .................................................................................................... 13

5.1 General ................................................................................................................. 13

5.2 Type of the sensors in IEC standards .................................................................... 14

5.2.1 General ......................................................................................................... 14

5.2.2 RTDs in IEC standards .................................................................................. 14

5.2.3 Thermocouples in IEC standards ................................................................... 14

5.3 Interface between the sensors and process in IEC standards ................................ 15

5.3.1 Thermowell .................................................................................................... 15

5.3.2 Cable connectors for temperature sensors ..................................................... 15

5.3.3 Cables of temperature sensors ...................................................................... 15

5.3.4 Sheath for temperature sensor cable ............................................................. 15

5.4 Ageing effects of temperature sensors .................................................................. 16

5.5 Environmental stressors ........................................................................................ 16

5.6 Techniques for detecting temperature sensor ageing ............................................ 17

6 Ageing management of temperature sensors ................................................................. 17

6.1 General ................................................................................................................. 17

6.2 Methodology of ageing management ..................................................................... 18

6.3 Ageing management program for temperature sensors ......................................... 18

6.4 Identification and assessment of ageing by performance verification tests ............ 19

6.5 Test and inspection interval .................................................................................. 19

6.6 Test location ......................................................................................................... 19

6.7 Calibration of measurement and test equipment (M&TE) ....................................... 19

6.8 Test and inspection results ................................................................................... 20

6.9 Validation of test methods ..................................................................................... 20

6.10 Classification of condition monitoring system and its software ............................... 20

6.11 Replacement of sensor or its parts ........................................................................ 20

7 Acceptable means for sensor testing ............................................................................. 20

8 Relationship between initial qualification and sensor ageing management ..................... 21

Annex A (informative) Performance verification of temperature sensors ............................... 22

A.1 Tests – Verification of performance ....................................................................... 22

A.2 Calibration test of temperature sensors ................................................................. 23

A.2.1 General ......................................................................................................... 23

A.2.2 Comparison of traditional calibration and online calibration method ............... 23

A.3 Response time testing .......................................................................................... 24

A.4 Uncertainty of elements for the sensors ................................................................ 24

A.5 Corrective actions for inoperable sensors ............................................................. 25

A.6 Alternative method with online testing ................................................................... 26

A.7 Documentation of calibration ................................................................................. 26

Annex B (informative) IAEA and IEC standards related to ageing management of the

sensors ................................................................................................................................. 27

---------------------- Page: 4 ----------------------
IEC 62765-2:2019 © IEC 2019 – 3 –

Annex C (informative) Tolerances of temperature sensors in international standards ........... 28

C.1 General ................................................................................................................. 28

C.2 ITS-90................................................................................................................... 28

C.3 Tolerance classes of temperature sensors ............................................................ 28

C.4 Calibration tolerance ............................................................................................. 29

Annex D (informative) Development of a plant ageing management program of

temperature sensors ............................................................................................................. 30

D.1 General ................................................................................................................. 30

D.2 Key steps for AMP of temperature sensors ........................................................... 30

D.3 Ageing management program ............................................................................... 31

Bibliography .......................................................................................................................... 33

Figure 1 – Schematic diagram of a TC (sourced from IEC 62651) ......................................... 14

Figure 2 – Conceptual methodology of ageing management processes ................................. 18

Table 1 – Examples of ageing effects and their potential causes ........................................... 16

Table 2 – Examples of environmental stressors with potential consequence ......................... 17

Table A.1 – Consideration for verification of performance test .............................................. 22

Table A.2 – Type test, routine test, and additional test for RTD ............................................. 23

Table A.3 – Comparison of concerns of calibration methods ................................................. 24

Table A.4 – Examples of uncertainty issues for RTDs ........................................................... 25

Table A.5 – Required example actions followed by acceptance criteria ................................. 25

Table B.1 – IAEA standards related to ageing management .................................................. 27

Table B.2 – Ageing management standards for the sensors in IEC standards ....................... 27

Table C.1 – Tolerance classes of typical temperature sensors .............................................. 29

Table D.1 – Key steps for the ageing management program of temperature sensors ............ 31

Table D.2 – An example of AMP guidance sheet for the sensors ........................................... 32

---------------------- Page: 5 ----------------------
– 4 – IEC 62765-2:2019 © IEC 2019
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
NUCLEAR POWERS PLANTS –
INSTRUMENTATION AND CONTROL IMPORTANT TO SAFETY –
MANAGEMENT OF AGEING OF SENSORS AND TRANSMITTERS –
Part 2: Temperature sensors
FOREWORD

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International Standard IEC 62765-2 has been prepared by subcommittee 45A:

Instrumentation, control and electrical power systems of nuclear facilities, of IEC technical

committee 45: Nuclear instrumentation.
The text of this International Standard is based on the following documents:
FDIS Report on voting
45A/1218/FDIS 45A/1227/RVD

Full information on the voting for the approval of this International Standard can be found in

the report on voting indicated in the above table.

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

---------------------- Page: 6 ----------------------
IEC 62765-2:2019 © IEC 2019 – 5 –

A list of all parts in the IEC 62765 series, published under the general title Nuclear power

plants – Instrumentation and control important to safety – Management of ageing of sensors

and transmitters, can be found on the IEC website.

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to

the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates

that it contains colours which are considered to be useful for the correct

understanding of its contents. Users should therefore print this document using a

colour printer.
---------------------- Page: 7 ----------------------
– 6 – IEC 62765-2:2019 © IEC 2019
INTRODUCTION
a) Technical background, main issues, and organisation of the standard

With the majority of NPPs over 30 years old, the management of ageing of temperature

sensors is currently a relevant topic, especially for those plants that have extended their

operating licenses or are considering this option. This standard is intended to be used by

operators of NPPs (utilities), systems evaluators, vendors, and by licensors. In the

international temperature measurement, the scale of temperature has been updated with ITS-

90 since it was published in 1990, so it is necessary that ITS-90 should be addressed in the

standard to cover the calibration of measuring and test equipment for temperature sensors.

b) Situation of the current standard in the structure of the IEC SC 45A standard series

IEC 62765 is the third level IEC SC 45A document comprised of several parts to tackle the

specific issue of management of ageing of sensors and transmitters in nuclear power plants

(NPPs) for I&C systems important to safety. Part 2 of IEC 62675 is dedicated to temperature

sensors.

IEC 62342 is the second level standard of SC 45A covering the domain of the management of

ageing of nuclear instrumentation systems used in NPPs to perform functions important to

safety. IEC 62342 is the introduction to a series of standards to be developed by IEC SC 45A

covering the management of the ageing of specific I&C systems or components such as

electrical cabling systems (IEC 62465), and sensors and transmitters (IEC 62765).

IEC 62765-2 is to be read in association with IEC 62342 and IEC TR 62096, which is the

appropriate IEC SC 45A Technical Report that provides guidance on the decision for

modernisation when the management of ageing techniques is no longer successful. For more

details on the structure of the IEC SC 45A standard series, see item d) of this introduction.

c) Recommendations and limitations regarding the application of this standard

It is important to note that this standard establishes no additional functional requirements for

safety systems. Ageing mechanisms have to be prevented and thus identified by performance

measurements in order to minimize their impact on sensor reliability. Aspects for which

special recommendations and limitations have been provided in this standard are:
• criteria for the evaluation of ageing of temperature sensors in NPPs;

• steps to be followed to establish the temperature sensor testing requirements for an

ageing management program for NPP instrumentation systems; and

• relationships between on-going qualification analysis and ageing management program

with regard to temperature sensors.

It is recognised that testing and monitoring techniques used to evaluate the ageing condition

of NPPs’ sensors and transmitters are continuing to develop at a rapid pace and that it is not

possible for a standard such as this to include references to all modern technologies and

techniques.

This standard identifies minimum requirements aimed at ensuring that any potential impacts

on NPP safety due to the ageing of temperature sensors of NPPs can be identified and that

suitable actions are undertaken to demonstrate that the safety of the plant will not be

impaired. To ensure that this standard will continue to be relevant in future years, the

emphasis has been placed on issues of principle, rather than specific technologies.

d) Description of the structure of the IEC SC 45A standard series and relationships

with other IEC documents and other bodies documents (IAEA, ISO)

The top-level documents of the IEC SC 45A standard series are IEC 61513 and IEC 63046.

IEC 61513 provides general requirements for I&C systems and equipment that are used to

perform functions important to safety in NPPs. IEC 63046 provides general requirements for

electrical power systems of NPPs; it covers power supply systems including the supply

---------------------- Page: 8 ----------------------
IEC 62765-2:2019 © IEC 2019 – 7 –

systems of the I&C systems. IEC 61513 and IEC 63046 are to be considered in conjunction

and at the same level. IEC 61513 and IEC 63046 structure the IEC SC 45A standard series

and shape a complete framework establishing general requirements for instrumentation,

control and electrical systems for nuclear power plants.

IEC 61513 and IEC 63046 refer directly to other IEC SC 45A standards for general topics

related to categorization of functions and classification of systems, qualification, separation,

defence against common cause failure, control room design, electromagnetic compatibility,

cybersecurity, software and hardware aspects for programmable digital systems, coordination

of safety and security requirements and management of ageing. The standards referenced

directly at this second level should be considered together with IEC 61513 and IEC 63046 as

a consistent document set.

At a third level, IEC SC 45A standards not directly referenced by IEC 61513 or by IEC 63046

are standards related to specific equipment, technical methods, or specific activities. Usually

these documents, which make reference to second-level documents for general topics, can be

used on their own.

A fourth level extending the IEC SC 45A standard series, corresponds to the Technical

Reports which are not normative.

The IEC SC 45A standards series consistently implement and detail the safety and security

principles and basic aspects provided in the relevant IAEA safety standards and in the

relevant documents of the IAEA nuclear security series (NSS). In particular this includes the

IAEA requirements SSR-2/1, establishing safety requirements related to the design of nuclear

power plants (NPPs), the IAEA safety guide SSG-30 dealing with the safety classification of

structures, systems and components in NPPs, the IAEA safety guide SSG-39 dealing with the

design of instrumentation and control systems for NPPs, the IAEA safety guide SSG-34

dealing with the design of electrical power systems for NPPs and the implementing guide

NSS17 for computer security at nuclear facilities. The safety and security terminology and

definitions used by SC 45A standards are consistent with those used by the IAEA.

IEC 61513 and IEC 63046 have adopted a presentation format similar to the basic safety

publication IEC 61508 with an overall life-cycle framework and a system life-cycle framework.

Regarding nuclear safety, IEC 61513 and IEC 63046 provide the interpretation of the general

requirements of IEC 61508-1, IEC 61508-2 and IEC 61508-4, for the nuclear application

sector. In this framework IEC 60880, IEC 62138 and IEC 62566 correspond to IEC 61508-3

for the nuclear application sector. IEC 61513 and IEC 63046 refer to ISO as well as to IAEA

GS-R part 2 and IAEA GS-G-3.1 and IAEA GS-G-3.5 for topics related to quality assurance

(QA). At level 2, regarding nuclear security, IEC 62645 is the entry document for the

IEC SC 45A security standards. It builds upon the valid high level principles and main

concepts of the generic security standards, in particular ISO/IEC 27001 and ISO/IEC 27002; it

adapts them and completes them to fit the nuclear context and coordinates with the

IEC 62443 series. At level 2, IEC 60964 is the entry document for the IEC/SC 45A control

rooms standards and IEC 62342 is the entry document for the ageing management standards.

NOTE 1 It is assumed that for the design of I&C systems in NPPs that implement conventional safety functions

(e.g. to address worker safety, asset protection, chemical hazards, process energy hazards) international or

national standards would be applied.

NOTE 2 IEC SC 45A domain was extended in 2013 to cover electrical systems. In 2014 and 2015 discussions

were held in IEC SC 45A to decide how and where general requirements for the design of electrical systems were

to be considered. IEC SC 45A experts recommended that an independent standard be developed at the same level

as IEC 61513 to establish general requirements for electrical systems. Project IEC 63046 is now launched to cover

this objective. When IEC 63046 is published this NOTE 2 of the introduction of IEC SC 45A standards will be

suppressed.
---------------------- Page: 9 ----------------------
– 8 – IEC 62765-2:2019 © IEC 2019
NUCLEAR POWERS PLANTS –
INSTRUMENTATION AND CONTROL IMPORTANT TO SAFETY –
MANAGEMENT OF AGEING OF SENSORS AND TRANSMITTERS –
Part 2: Temperature sensors
1 Scope

This part of IEC 62765 identifies minimum requirements and applicable practices for

correcting and preventing any potential impacts on nuclear power plant (NPP) safety due to

the ageing of temperature sensors, such as NPP resistance temperature detectors (RTDs)

and thermocouples (TCs).

This document provides strategies, technical requirements, and recommended practices for

the management of the ageing of temperature sensors important to safety in nuclear power

plants (NPPs) to ensure that ageing can be identified and that suitable remedial actions are

undertaken as necessary to demonstrate that the safety of the plant will not be impaired. This

document is aligned with IEC 62342, which provides guidance on ageing management for

instrumentation and control (I&C) systems important to safety in NPPs.

IEC 62765 standard series covers pressure transmitters (Part 1) and temperature sensors

(Part 2). Part 1 covers pressure transmitter (PT), level transmitter
...

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